1. Field of the Invention
The present invention relates to a projector device and a theft preventing method.
2. Description of the Related Art
In recent years, a growing number of projector devices have been stolen as they can be carried and are relatively expensive. Therefore, it is necessary to take some measures to prevent projectors from being stolen.
It has been customary to prevent a projector device from being stolen by either incorporating a theft prevention system into the projector device or attaching a theft prevention system to the projector device.
According to the former theft preventing scheme, the projector device is shut off by setting a password or using a PC card.
There are various types of the latter theft preventing systems. For example, Patent Document 1 (JP-A-10-111991) discloses a theft detector for detecting whether the projector device is moved or not with an acceleration sensor. The disclosed theft detector issues an alarm signal when the acceleration sensor detects a movement of the projector device.
Patent Document 2 (Japanese patent No. 3163242) reveals a method of and an apparatus for preventing a theft by estimating a distance that the projector device has moved with an acceleration sensor, and detecting a theft based on the total estimated distance.
According to the process of shutting off the projecting device by setting a password or using a PC card, however, the user needs to enter the password or insert the PC card each time the user is to use the projector device. Therefore, the process is tedious and time-consuming.
The theft detector disclosed in Patent Document 1 does not require the user to enter a password or insert a PC card because the acceleration sensor detects whether the projector device is moved or inclined.
However, since the projector device is often moved within a building or the like, theft detector disclosed in Patent Document 1 is possibly liable to detect a theft in error each time the projector device is moved. To avoid such a wrong theft decision, projector settings need to be changed or the theft detector needs to be removed from the projector device each time the projector device is to be moved. Consequently, the disclosed theft detector is cumbersome to use. The theft detector is not sufficiently effective for projector devices whose installed locations are often moved from place to place.
The theft preventing apparatus disclosed in Patent Document 2 estimates a distance that the projector device has moved with an acceleration sensor, and detects a theft based on the total estimated distance. The disclosed theft preventing apparatus does not require projector settings to be changed each time the projector device is to be moved. However, when the projector device changes its installed location, e.g., when the projector device is moved within one room, the projector device may be judged as being stolen based on the total distance that the projector has been moved.